Exemplary embodiments of the present invention are directed to an airbag and a method for producing such an airbag.
In the mass production of motor vehicles protective devices are known, which comprise air pouches, so-called airbags, which are constructed with a container of variable volume for air. In the event of an impact of the motor vehicle against a barrier, the airbags are inflated by a gas discharge in a very short time.
This serves the purpose of protecting occupants of the motor vehicle from impacting against components in a passenger compartment. This inflation and the protective function must take place very quickly, because there is very little time available for inflation in the event of such an impact. There is potential for reducing the cost of such airbags.
Exemplary embodiments are directed to an airbag, in particular an air pouch, and a method for producing such an airbag, which enable the airbag to be produced inexpensively.
An airbag, in particular an air pouch according to the invention, comprises a valve device for a gaseous medium, with at least one textile layer and at least one foil that covers at least some of the textile layer in such manner that by means of the valve device at least one area of the airbag permeable to the medium can be at least partially opened when the valve device is in an open position and can be at least substantially sealed when the valve device is in a closed position. In relation to the medium, the textile layer is, for example, designed to be permeable by the medium, whereas the foil is, for example, formed of a material that is essentially impermeable to the medium. In the open position the medium can therefore flow through the textile layer and through the permeable area. By integrating the valve function in the at least one foil and textile layer and integrating the valve device in the airbag, the airbag according to the invention has a very small number of parts and is therefore inexpensive. Moreover, not much complexity is involved in producing the airbag and this too reduces costs even more.
Since the foil is already provided in order to ensure that the airbag remains functional for a certain time, i.e., that it continues for a period of time to provide a supporting and therefore protective function for the occupants of a motor vehicle fitted with such an airbag, the airbag according to the invention can be produced in a small number of process steps and therefore quite quickly and inexpensively. Moreover, it takes up only little space and this avoids and/or solves stowing problems.
The valve function of the valve device comprising the textile layer and the foil is provided by the co-operation of the foil with the textile layer. In this, the foil functions as the flap of the valve device, which can influence or control the flow of the medium through the textile layer in one direction and in the direction opposite thereto. The textile layer functions as protection against puncturing the foil that acts as the flap, so that in the open position of the valve device the medium can flow in through the permeable area of the textile layer, while in the closed position of the valve device the flow of medium through the permeable area is at least substantially blocked.
Furthermore, the valve function of the valve device enables a large quantity or mass of the medium to flow particularly well, rapidly and efficiently through the valve device in a very short time, which is a great advantage since the airbag has to be filled very quickly with a minimum quantity of the medium, in particular air, in order to ensure a large and rapid volume increase to protect the occupants of a motor vehicle fitted with such an airbag.
In addition to this very advantageous functionality of the valve device in the airbag according to the invention, a further advantage is that it is only very light and takes up only a small volume when stowed. This is so because the foil and the textile layer are both extremely thin and their respective weights are very low. This also reduces the cost of the airbag according to the invention because both the foil and the textile layer, being products manufactured by the meter, can in each case be produced quickly and cheaply.
Thus, the airbag according to the invention is formed, for example, as a large, one-piece air pouch which, in its inflated condition, takes up a certain, desirably large volume in the inside space of the motor vehicle. In such an application the valve device serves during inflation or volume-enlargement of the airbag, to allow a desired mass or quantity of air to flow into the airbag when the valve device is in its open position. If the airbag is inflated and a passenger is thrown against it, then in its closed position the valve device keeps the air at least for the most part inside the airbag and prevents and outflow and/or too rapid an outflow of the medium out of the airbag, in order to ensure a certain, desired degree of support by the airbag.
Likewise, the airbag according to the invention can be in the form of a so-termed frame structure bag which, for example, has a frame structure consisting of a plurality of tube elements each of variable volume, which in the event of an accident-related force impact on the motor vehicle, are inflated so as also to occupy a certain volume in the inside space of the motor vehicle. Such a frame bag, compared with the above-described one-piece airbag, has advantages in that the frame structure occupies just as large a volume inside the vehicle and therefore has at least as good a supporting function as the first type of airbag, but has a smaller total volume that has to be acted upon, i.e., inflated by the medium. In other words, this means that the individual volumes of the tube elements, when summed, can be smaller than the volume of the large, one-piece airbag but despite this, by virtue of the frame structure formed by the tube elements, the frame bag occupies a volume at least equal to that of the one-piece airbag inside the vehicle and can thus have the same supporting and protective function for the occupants.
In this case the frame structure is clad with a cover, in particular made of fabric, to improve its supporting function, so that by virtue of the frame structure and the cover an inside space of the frame bag is formed, which is filled with a medium, for example air and in particular air from the surroundings, in order to further improve the supporting function of the frame bag. In this case the cover of the frame bag is advantageously formed at least in part by the textile layer and foil or the valve device of the airbag according to the invention, which makes it possible to fill the inside space delimited by the frame structure and the cover with a large quantity of medium, in particular surrounding air, in a short time. Thus, the inside space can be regarded as analogous to the large, one-piece and first-mentioned airbag, and provides at least the same supporting and protective function as the latter, whereas the frame bag can do this in a shorter time. Putting it the other way round, this means that in the same time it can expand to a larger volume than the aforesaid one-piece airbag and so provides a better supporting and protective action. Yet even with the large one-piece airbag the valve device provides the advantage that it can be inflated very quickly with a particularly large mass or quantity of the medium.
Inherent in the textile layer is the advantage that it forms a homogeneous surface which, if an occupant is thrown against it, avoids or at least reduces the risk of injury to the occupant, especially in the head area. In an embodiment of the invention the aforesaid permeation area is in the form of at least one gap in the foil, formed for example by perforation. This perforation can be produced, for example, during the production of the foil by means of a “porcupine” roller that forms a plurality of such perforations in the foil, resulting in particularly inexpensive production and enabling a very effective and good valve function of the airbag device.
In an advantageous embodiment of the invention at least one flap element that corresponds to the at least one perforation of the foil is provided, which in the at least temporary open position of the valve device leaves the at least one perforation at least partially unobscured, and in the closed position of the valve device at least partially blocks it. In this case the flap element is advantageously made integrally with the foil, so that again a small number of components, low weight and low costs of the airbag are entailed.
Alternatively or in addition, in another embodiment of the invention the permeable area is formed by at least one foil area that can be raised clear of the textile layer in the open position. To improve the sealing action in the closed position, in one embodiment this is closed off by at least two foil areas that overlap when the valve device is in the closed position. This means that the foil has at least two overlapping areas, which in turn cover an area of the textile layer. The overlapping foil areas at least partially leave clear the textile layer when the valve device is in the open position and at least substantially closes it when the valve device is in the closed position. On the one hand this enables a particularly efficient and very good flow of the medium through the valve device, and on the other hand particularly efficient and effective blocking of the flow in the corresponding opposite flow direction of the medium.
The invention also relates to a method for producing an airbag, in particular a bag for gas, with a valve device for a gaseous medium, having at least one textile layer and at least one foil arranged to cover at least part of the textile layer. By means of the valve device at least one area of the airbag permeable by the medium can be opened at least partially when the valve device is in an open position, and can be at least substantially sealed when the valve device is in its closed position. Advantageous design features of the airbag according to the invention should be viewed as advantageous features of the method according to the invention, and conversely.
The foil is, for example, laminated onto the textile layer, bonded to the textile layer in some areas and/or stitched thereto, and advantageously, already during these or any other ways of joining the foil to the textile layer, it is designed to form the valve device. This entails an integration and thus parallelization of production steps, which keeps down the production time and thereby reduces the production costs for the airbag made by the method according to the invention. Thus, the method according to the invention also makes it possible to produce an inexpensive airbag that nevertheless ensures very good functionality for the protection of occupants of a motor vehicle fitted with such an airbag.
If the permeable area is in the form of at least one opening in the foil, then this is produced, for example, as a perforation by means of a porcupine roller which perforates the foil of the valve device of the airbag according to the invention, for example while it is being laminated onto the textile layer.
Further advantages, features and details of the invention emerge from the following description of a number of preferred example embodiment and with reference to the drawing. The features and combinations thereof mentioned in the description above, and below in the description of the figures, and/or those illustrated in the figures alone, can be used not only in the combinations specifically indicated but also in other combinations or in isolation, without going beyond the scope of the invention.